Apparatus for testing the static balance of propeller blades



Feb. 17, 1948.

L. B. 'CHUBB APPARATUS FOR TESTING THE STATIC BALANCE OF PROPELLERBLADES Filed May 14, 1945 3 Sheets-Sheet Fri .Feb. 17, 1948. V L.B.HUBB2.436.096

APPARATUS FOR TESTING THE STATIC BALANCE 0F PROPELLER BLADES I Filed May14, 1943 3 Sheets-Sheet 2 Lenqgb. (1/5116!) Feb. 17, 1948.

L. B. CHUBB APPARATUS FOR TESTING THE STATIC BALANCE OF PROPELLER BLADESFiled May 14, 1943 3 Sheets-Sheet 3 Patented Feb. 1'7, 1948 APPARATUSFOR TESTmG THE STATIC BALANCE OF PROPELLER BLADES Leroy B. Chubb,Toledo, Ohio, assignor to Avco Manufacturing Corporation, a corporationof Delaware Application May 14, 1943, Serial No. 487,000

20 Claims. 1

The invention relates to apparatus for use in making propeller blades.

In the fabrication of hollow steel propeller blades it is desirable andimportant for the proper performance of the blade to finish the tubularshank end of the blade, which is usually rotatably confined in a radialsocket in the hub for pitch variation, according to the hanging verticalcenter line of the blade when it is suspended in vertical hangingbalance rather than according to its physical longitudinal axis. In thefabrication of these blades in production equipment discrepanciesbetween said axis and said hanging center line are practicallyunavoidable and this renders it necessary to machine the shank for itsproper performance in the hub.

One object of the invention is to provide improved apparatus formeasuring the variation at the tip of the blade between the physicallongitudinal axis and the hanging vertical center line for use inmachining the internal and external peripheries of the shank so that theaxis of the shank, when installed in a hub, will be coincident with thetrue vertical center line of gravity or hanging vertical center line ofthe blade.

Another object of the invention is to provide improved apparatus forexpediting the manipulation of the propeller blades for determining thevariation between the physical longitudinal axis and the true hangingvertical center line.

Another object of the invention is to provide a simple, efficient andquickly attachable and detachable device for internally gripping theshank of the blade for hanging the blade on an abutment' on the flexiblesuspension element.

Another object of the invention is to provide a device which is adaptedto gripand is quickly attachable to and detachable from the flexiblesuspension element such as a wire, for hanging the blade from its shankwhile making measurements at the tip.

Other objects of the invention will appear from the detaileddescription.

The invention consists in the several novel features which arehereinafter set forth and more particularly defined by claims at theconclusion hereof.

In the drawings:

Fig. 1 is a front elevation of apparatus embodying and for carrying outthe invention.

Fig. 2 is a vertical central transverse section.

Fig. 3 is a vertical section of the device detachably secured in theshank of the blade and the detachable device for gripping the suspension2 Wire for suspending the blade from a hanging center in the shank ofthe blade.

Fig. 4 is a section taken on line 4-4 of Fig. 3.

Fig. 5 is a section taken on line 55 of Fig. 3.

Fig. 6 is a section taken on line 6-6 of Fig. 3.

Fig. 7 is a plan view of parts of the device which are secured in theshank of the blade for suspension of the blade from the wire.

Fig. 8 is a section taken on line 8-8 of Fig. 5.

Fig. 9 is a vertical section of the Viewing and measuring device.

Fig. 10 is a section taken on line Ill-l 0 of Fig. 9.

Fig. 11 is a plan ofthe lens and the casing in which it is mounted.

Fig. 12 is a diagram illustrating the manner of determining the locationof the hanging vertical center line at the tip of the blade from thephysical longitudinal axis of the blade.

In the fabrication of the blade a the working portions of the blade arefinished to airfoil contour and the shank a is rough finished. A point ais prieked in the tip at the physical longitudinal axis for use inmeasuring the hanging vertical center line at the tip of the blade. Theblade is then elevated and suspended so it will hang in verticalbalance. While hanging in vertical balance, the tip end of the blade isviewed andthe location of the hanging vertical center line ismicrometrically measured from the point a These measurementsv are thenused in'machining the interior andexterior peripheries-of the shank soits axis will conform to the true g. center line of the blade. Theblade. is placed in a cylindrical fixture or. jig with the true hangingcenter line congruent with or lying along the center line in the jig.The jig is, then placed in suitable equipment so that the internal andexternal surfaces of the hub may be machined parallel'to the hangingcenter line of the blade. In assembling the blade into the jig the pointa is again utilized by positioning it away from the center line of thejig according to the measurements as determined by the micrometerreadings taken when the blade was in hanging balance in the hangingfixture.

The apparatus exemplifying the invention comprises, generally: aflexible element such asfa wire for suspending the blade in hangingbalance; a detachable abutment device on the suspension wire on whichthe blade is free to hang in vertical balance; a device which isdetachably secured in the bore of the shank of the propeller forsuspending the blade in hanging balance from the abutment device:hoisting mechanism comprising a winding drum for the wire for raisiv ingand lowering the blade from its shank into its hanging position; acolumnar supporting structure; an overhead device for gripping the wireabove the blade for holding the latter in an elevated hanging position;a device controlled from floor level for operating the overhead grippingdevice; an optical unit for viewing from below the tip of the blade; andmeans for measuringthe variation between the point indicating thephysical longitudinal axis and the hanging vertical center line when theblade is suspendedi hanging balance.

The supporting structure comprises a solid concrete base which isusually built on a solid foundation under the shop floor 2i; apair ofconcrete columns 23 built on the base 20 and spaced apart to providebetween them a vertically extending space in which the propeller blade acan be suspended; a plate 22 rigidly mounted on the base 2d atconvenient working level for the operator; andtI-beam 24 which rigidlyconnects the top of the columnszti; and a frame 25 rigidly mounted onthe top ofll-beam 24 for supporting a sheave, 2!- which is journaled in.a bracket. 28' which is welded tov the top of the frame 25. A suspensionwire 26 has a portion which. depends from the sheave 21 for attachmentto the propeller blade. An overhead electric hoisting mechanism 279 is.mounted on the beam and comprises a drum 39 on which the wire 25 iswound to hoist the blade; connected to the freeend of the wire 25 fromthe floor into suspended position between the: columns 23. Rungs 19secured in the base 20 and columns form a ladder on which an operatorcan climb to theupper portion of the supportingstructure.

Theabutment-device for supporting the shank end of the blade forvertical hanging balance fromthe wire Zioomprises a body or thimble 35through which the-wire 26 passes and which is provided witha notchedgripping flange or wheel 38; a conical socket 39. and an: internalscrewthread 31. A gripping member 32-- comprises a stem 32 which isthreaded to the screwthread 3-1 in. the thimble 36 and provided with awheel or grip 33 at itslower end, a seriesof longitudinally extendingradial slots- 35 which formcontractible jaws for gripping thewire 2G,and a conicalportion 40 fitting: inthe conical socket 39- inthethimble3B; Thimble 36 and member-32' have acentral opening through which thewire 26- passes. In attaching the abutment device to' wire 25, thewireis threaded through thimble 36 and member 32 and the thimble 36 isthen rotated around member 32 which will cause the conical socket 391 tocontract the jaws on member 32- and' forcethem-into firm grippingrelation with the wire. Reverse rotation of the thimble will permitthejawsonmember 32 to expand and release the. wire. The upper end ofthimble 35- for suspending the blade on the hemisphericalabutmentsurface 41' of the thimble 36 comprises acylindricalbodyAG-whichisad'apted to extend freely-into the bore of the shank of the blade and.is provided with a peripherally notched flange 41' adapted to abutagainst the end of theshank; a 'series of'wedges SO-Which areradially 4slidable in slots 54 in the body 46; and an expanding sleeve 45 whichextends through body 46 and comprises a cone 5| which engages and isadapted to spread the wedges 5B in the bore of the blade for internallygripping the shank. Sleeve 45 is slidable in the body 46 and isconnected thereto against rotation by a: spline 49. A. nut 48 isscrew-threaded to the upper end of the expanding sleeve 45, abutsagainst the upper face of flange 4! on body 46, and is adapted to slidethesleeve 4.5 in body 46 so that cone 5| will expand, the wedges 58 intointernal gripping engagement with the bore of the blade. Spring rings53. are adapted to contract the wedges 58 when the nut 48 is rotated onmember 4| to release the wedges 58; A bearing block 42 is seated againstthe shouldered upper end of a socket 15 in the expanding sleeve 45 andis provided with a conical surface 43 which engages the hemisphericalsurface 4! on. the member 36 of the wire gripping device so that theblade and the device clamped in the blade are free to permitthe blade tohang inverticalbalance. The thimble 3.6 extends into the socket 45 insleeve 45 blade hangs is coincident with the axis of the shank. Thisexpansible gripping device exemplifies one which is adapted to beclamped in the bore of the blade for freely suspending the blade fromthe abutment device which is clamped to the wire 26, so that the bladewill pass into true vertical hanging balance.

In usin the invention the shank gripping device with the bearing block42 therein is secured in the blade while the latter is on ornear thefloor and after the wire 25 has been threaded therethrough and? theabutment device has been secured on the wire. The drum 30 will then beoperated bythe hoisting device 29- to wind the wire 26, on the drum. Theabutment device on the wire will engage the gripping device in the shankof the blade and. elevate the blade until it is freely suspended inhanging balance with its tip a above'thebase 28 of the supportingstructure.

The invention comprises device for gripping the wire 25 to support theblade in hanging balance for. the determination of the discrepancybetween the physicallongitudinal axis and the hanging vertical centerline of the blade. This deviceis supported? above the hanging blade byan I-beam 55 which extends between the columns 23 and is secured toangle ironsfixed t'o saidcol umns. This gripping device is ,supportedina frame which comprises a block 56, bars. 51 welded to the top of saidblock, and-a bar 58 secured by screws 59to the bars 51. Theframeissupported from thev I-beam 55v by bolts 60. which extend: throughblock 58 and bars51 and 58. Avbearing block 6! is seated in a shoulderedrecess in block 56 and is provided with an upwardly facing conicalbearing surface. The wire 25' between the sheave 21 and the end-on whichthe blade is suspended extends through' a thimble or sleeve 63. Thelower end of sleeve 63 is provided with a hemisphericalbearing surface64- which engages the conical surface 62'inthe-block'6l A stem'65 isscrew-threaded at66- to the sleeve 63 and is provided with a conicallower end 61 which fits in a conical bore 68 in the sleeve 63 and withlongitudinal slits 69 so that the portions between the slits constitutecontractible jaws for gripping the wire. The cone 61 formed on the stem65, fits sleeve will contract the jaws on said stem and cause them togrip the wire 26. Reverse rotation of the stem will release said jaws topermit the wire to slide through the block 6|, sleeve 63 and stem 65.Lugs I6 fixed to block 56 extend loosely into notches II in a flange onthe upper end of sleeve 63 to hold said sleeve against rotation.Suflicient play of the lugs I6 in notches II is provided to permit thesleeve 63 and the stem 65 therein to tilt on the bearing block 6| sothat the wire will hang truly vertical from the sleeve 69.

This cable gripping device is elevated for suspending the blade abovethe base 26 and mechanism is provided for operating it conveniently byan operator on the floor 2 I. This mechanism comprises a hand wheel I2fixed to the lower end of a shaft I3 which is journaled in a bracketwhich is fixed to the front side of one of the standards 23; averticalshaft I4 journaled in the block 56 and bar 58 and connected by auniversal joint I5 to the upper end of shaft 13; a pinion I6 keyed toshaft 14 between bar 58 and block 56; a gear 11 meshing with pinion I6and journaled on a hollow stud I8 which is secured by a nut 19 in thebar 56; and a series of-pins 86 fixed in and depending from gear I1 andextending loosely into holes 8| in the flange 82 on the upper end of thestem 65. Holes 8| are enlarged to permit the sleeve 63 and the stem 65to tilt. The wire 26 extends through the stud 16. Before the hoistingdevice is operated to wind wire 26 on the drum 36 for hoisting the bladeto its elevated hanging position, the operator on the floor 2| willrotate the wheel I2 in one direction which will cause pinion I6 torotate gear 'I'! which car ries the pins 86 and the latter will rotatethe stem 65 tocause the screw-thread 66 to movethe stem 65.upwardly inthe sleeve 63. This will cause the jaws on the stem 65 to spread so thatthe wire 26 will pass through the stem 65 and sleeve 63. When the bladehas been elevated to its hanging position below the block 56, rotationof the hand wheel 12 in the opposite direction will rotate the stem 65into the cone 98 in the sleeve 63 and jamb the jaws on said stem intofirm gripping relation with the wire 26 so that the blade will besuspended at the fixed elevation desired. After the hanging center lineof the blade has been determinedas hereinafter set forth, the hand wheelI2 may be again operated to release the wire 26 so that the blade can belowered to floor level. This exemplifies means accessible from the floorfor operating the device for locking the depending portion of the wire26. Before the blade is hoisted to its hanging position a, point a ispricked in the tip on the physical longitudinal axis of the blade. Whenthe blade is elevated and suspended the wire 26 permits it to hang invertical balance around a vertical line extending through the center ofthe bearing between the sleeve 63 and the bearing block 6I. 'When thepoint a on the tip of the blade in hanging balance is not coincidentwith the hanging,

vertical center line, said point will be horizontally offset from thevertical. hanging center line in distance and direction according to thediscrepancy between the vertical hanging center line and the physicallongitudinal axis resulting from variations in the distribution of massin or in the machining of the blade.

An optical device is provided for viewing the tip of the blade andmicrometric means for measuring the variation between the point a whichindicates the physical longitudinal axis and the hanging vertical centerline at the tip of the blade while it is suspended in vertical hangingbalance. This optical device is mounted over the plate 22 at convenientworking level for the operator and comprises a, mounting or casing 9 I;a lens carried by a tube 96; a pinion 92 which engages rack-teeth 93 ontube 96 for focusing the lens 85'on the tip of the blade; a thumb wheel92 for rotating pinion 92; screws 94 engaging a shoe 95 for securingtube 96 with its lens therein in its adjusted position; an upwardly andforwardly inclined tube 86 with a suitable lens and eye-piece; andhoused prisms 81 and 68 which provide for vision from tube 86 of the tipof the blade through the lens 65. The lens 85 is provided with hairlines 96, 91 at right angles to each other which intersect in the centerof lens 85 and tube 96. The optical device with the lens 85 therein ismounted for movement in planes at right angles to each othercorresponding to the lines 96, 91 so that the intersection of lines 96,91 may be shifted longitudinally and transversely into verticalalignment with the point a on the physical longitudinal axis of theblade.

The mounting 9| is detachably and fixedly carried by a plate I66 whichis slidable horizontally and transversely under the tip of the blade ina plane parallel to the line 91 on lens 65 over a plate I65 which isslidable longitudinally on the fixed plate 22, so thatby compounding themovements of the plates I 66 and I65 the intersection of the lines 96,91 may be brought into vertical alignment with the point at on the tipof the blade while the latter is viewed by the operator. A screw I6! isconnected to plate I65, threaded to a lug I68 which is fixed on theplate 22, and provided with a stem I6'I for turning the screw topositively shift plate I65. A screw I69 is connected to plate I66,threaded to a lug II 6 which is integral with the plate I65, andprovided with a handle I69 for turning the screw to positively adjustthe plate I66 over the plate I65. The position of the plate I65 on theplate 22 is indicated by a pointer III and a scale II2 fixed to plate22. The position of the plate I66 on the plate I65 is indicated by apointer I I3 on plate I69 and a scale II6 fixed to plate I65. Thesescales are marked to indicate when the mounting 9| is adjusted tovertically align the intersection of lines 96, 91 on lens 65 with thehanging vertical center line of the blade when it is in true verticalhanging balance and also to indicate the distance which the mounting andlens are moved horizontally in directions at right angles to each otherto vertically align said intersection with the point a on the tip of theblade. As a result, when the intersection of the lines 96, 91 is shiftedhorizontally into vertical alignment with the point a on the tip of theblade, the coordinates X and Y, as illustrated in Fig. 12, will bemeasured on the scales H4, H2, respectively. In this manner thevariation or discrepancy between the physical longitudinal axis and; thehanging vertical. center .line. at; the tip of: the blade. will be:accurately. determined and measured; The mounting: Si is.- providedwith: albase flange-99S which is. d'etachably secured by clamping lugs98 to plate Hill. A circular plate I01 is clamped between theflangeilill and plate. I; The-baseflange BSYis provided with a stud i0?which fits into a hole in the; plate NH and the latter is provided witha cylindrical stud I03 which fits into a corresponding.- opening inplate I00; The base flange 93'is.pr0Vided' with notches 34' which, whenthe clamps 98; are loosened and the flangev 99 isrotat'ed. tobring'thenotches into alignment with lugs 9'8, will: permit the: mounting 9i tobe removed from 'theplate m0;

The optical device is partially enclosed: in. a housing H6 which isprovided with. an opening in its top for exposing the tip of theblade;

After the X and Y coordinates. have beenit-hus measured, the hand. wheel121 is operated to release the wire. 26 and the blade is lowered. Theshankgripping device is thenreleased. from the-blade and lefton.the'wire 26. The blade is then positioned in. a suitable fixture 01'.jig in accordance with the true hanging center line of the bladecoincident? with or lying along the center line of the jig. This jig: isthen placed: in a. suitable equipment: andxthe internal and external:surfaces: of the shank aremachined' parallel to the hanging center lineof the blade. In assembling. the blade into the jig the. blade ispositioned from the point a? and the center line of the jig'according tothe measured coordinates X and Y as determined by. the micrometricreadings taken: when the blade was" in the hanging fixture.

The invention exemplifies apparatus for expeditiously and accuratelydetermining and measuringthe discrepancy between the physicallongitudinal center line and the vertical center line of apropellerblade at its tipwhen the blade is in hanging balance for use inmachining or remachining'the shank of'the blade in accordance with its:true hanging center line to facilitate-the fabrication ofpropellerblades within permissible tolerances for mounting the blade inv a. hubin accordance with the hanging vertical center line andawhichresults inreducing the tolerance range.- The invention also exemplifies: a fixturefor conveniently handling'the-blade for hanging it in vertical balance;a conveniently operable device for controlling an: overhead device forgrippingthe wire to support the blade in elevated position; an abutmentdeviceadapted to be clamped to the suspension'wire; and a, devicewhichis adapted to internally grip the shank ofthe blade for suspensionfrom the abutment device on the wire;

The invention isnot to be understood as restricted'to the details setforth sincethese-may be modified within" thescope of the appended claimsWithout departing from the spirit and scope of theinventiom Having thusdescribed the invention, what I claim as new and desire to secure byLetters Patentis:

1 Apparatus for use in malcing'propeller blades provided with a shankfor connection to a hub: comprising; a supporting. structure; meansadapted" to: be. connected to the: shank. of the bladefor suspending theblade. from; saidstructure so itis free to. hang vertically with'the tipat. its lower end; and an optical device-on: said structure for viewingthe tip-of the bladefrom below; including: meansfor. measuring: thedeviationbetween the. vertical:v line of; the hanging centerand: a markon the: physical longitudinal axis at the. tip. of the blade in;difierent. angular directions.

2. Apparatustfor usein makin'gtpropellerblades provided with. a shankfor: connection to a hub comprising, a. supporting. structure; meansadapted to be. connected to the: shank of. the blade for suspendingth8.':b1&de'. from saidstructure so it is. free to'hang vertically with'the tip at its lower: end, and; an optical device on: said structure;for viewing the tip of the blade from below including means for: moving;said device in horizontal planes in directions at right angles to eachother, and means; formeasurin'g: in said planes the deviation between:the vertical lineof the. hanging: center and a mark. on the physicallongitudinal axis at. the. tip of the. blade in dif, ferent angulardirections.

3. Apparatus-for use. in maklng'propell'er blades provided. with ashank. for. connection: to. a hub comprising, a supporting structuremeans adapted to be: connected to the shank of. the blade. forsuspending the blade from. said; structure so it is free. tohangvertically with the tip at its. lower. end, and; an optical device; onsaid structure for viewing: the tip of the; bladeafiom below comprisinga lens below the. blade and provided with means movable to verticalcoincidence with a. point on the tip of: the blade, an: eye-piece inofiset relation .to the blade, prisms between the lens and the.eyeepiece, andm'eans for measuring the deviation between the verticalhanging: center line and a mark on thephysical longi tudinal axis atthetip of the blade in different angular directions,

4. Apparatusfor use in making propeller blades provided with a shankfor. connection to a hub comprising, a supporting structure, meansadapted to be. connected to the. shank of the blade for suspending theblade from said strumture so it is free tohang vertically with the tipat its lower end, an optical device. on saidstruc' ture for viewing thetip of the blade from below including, a lens below the blade, aneye-piece in offset relation to'the blade; prisms between the lens andtheeye-piece, and amountin for the lens; eye-piece and prisms, movablein horizontal planes in directions at: righti'angles to each other topositionthe. lens. in vertical alignment with amarkedphysical centeronthe tip of the blade, and means carried by said mounting for measuringin said planes the distance between the vertical line of" the hangingcenter and a mark on the-physical longitudinal axisat the tip of theblade.

5'; Apparatusfor usein-making propeller blades provided with a shank forconnection to a hub comprising, a rigid columnar supporting structure;a. flexible suspension element for the blade carried by the structureand havinga depending end-portion, hoisting mechanism supported on thestructure and connected to' said element for. raising the blade intoafreely hang,- ing position, means. on the depending portion of theelement. for supporting the blade,.a device on the supporting, structurefor gripping. said element to hold the blade in a predetermined hangingposition, meansior. operating the. gripping device tosecure and release.said element, and means below and for determining the deviation of.amark on the physical longitudinal V .tip of the blade.

l 6. Apparatus for use in making propeller blades provided'with a shankfor connection to a hub comprising, a rigid columnar supportingstructure, a flexible suspension element for the blade carried by thestructure and having a depending end-portion, a sheave at the top of thestructure around which the element extends, elevated hoisting mechanismsupported on the structure and'connected to the other end of saidelement for raising the blade into a freely hanging position, means onthe depending portion of the element for supporting the blade, a deviceon the supporting structure for gripping said element to hold the bladein a predetermined hanging position, means for operating the grippingdevice to secure and release said element, and optical means below andfor determining the deviation of a mark on the physical longitudinalaxis from the vertical hanging center line at the tip of the blade.

7.' Apparatus for use in making propeller blades provided with a shankfor connection to a hub comprising, a flexible element having adepending portion for a hanging connection to the shank of' the blade, adevice for gripping said element to support the blade in hangingposition comprising a member provided with contractible jaws forgripping said element and a body to which said member is screw-threadedand provided with means for contracting the jaws to grip the element,said body and member having a central opening through which said elementpasses, bearing-means for supporting said bodymember so the member andbody tilt in any direction, means for holding the body against rotation,and means for rotating said member in the body.

8. Apparatus for use in making propeller blades provided with a shankfor connection to a hub comprising, a flexible element having adepending portion for a hanging connection to the shank of the blade, adevice for gripping said element to support the blade in hangingposition comprising a member provided with contractible jaws forgripping said element and a body to which said member is screw-threadedand provided with means for contracting the jaws to grip the element,said body and member having a central opening through which said elementpasses, bearing-means for supporting said bodymember so the member andbody are free to tilt in any direction, a stationary support for thebearing-means, means between the support and body, for holding the bodyagainst rotation while permitting it to tilt, and means for rotatin saidmember in the body.

9. Apparatus for use in making propeller blades provided with a shankfor connection to a hub comprising, a flexible element having adepending portion fora hanging connection to the shank of the blade, 2.device for gripping said element to support the blade in hangingposition comprising amember provided with contractible jaws for grippingsaid element and a body to which said member is screw-threaded andprovided with means for contracting the jaws to grip the element, saidbody and member having a central opening through which said elementpasses, bearing-means for supporting said bodymember so the member andbody are free to tilt in any direction, a stationary support for thebearing-means, means between the support and body, for holding the bodyagainst rotation, and

gearing for rotating saidmember mounted on the support, and a loosedriving connection between the gearing and said member which permitssaid member to tilt in any .direction.

10. Apparatus for use in making propeller blades provided with a shankfor connection to a hub comprising, a flexible element having adepending portion for a hanging connection to the shank of the blade, adevice for gripping said element to support the blade in hangingposition comprising a member provided with a screw-threaded stem havingcontractible jaws for gripping said element and a body member with ascrew-thread for said stem and provided with means for contracting thejaws to grip the element, said stem and body having a central openingthrough which said element passes, bearing-means for supporting saidbody so the body and stem are free to tilt in any direction, means forholding the body against rotation, and means for rotating said member inthe body.

11. Apparatus for use in making propeller blades provided with a shankfor connection to a hub comprising, a flexible element havinga'depending portion for a hanging connection to the shank of the blade,a device for gripping said element to' support the blade in hangingposition comprising a member provided with contractible jaws forgripping said element and a body to which said member is screw-threadedand provided with means for contracting the jaws to grip the element,said body and member having a central opening through which the elementpasses, a stationary support, a bearing carried by the support whichpermits said body and member to tilt in any direction, means between thesupport and the body for holding the body against rotation whilepermitting such tilting movement, and gearing carried by said supportfor rotating said member in the body while permitting said member totilt.

12. Apparatus for use in making propeller blades provided with a shankfor connection to a hub comprising, a supporting structure including apair of rigid columns extended upwardly from a working floor and spacedapart laterally to provide between-them space for hanging theblade, aflexible suspension element for the blade having a depending end-portionbetween the columns, means for detachably supporting the blade on theend of the depending portion of the element, hoisting mechanismsupported on' the structure and to which the element is connected forraising the blade into hanging position between the columns, an overheaddevice on the supporting structure for gripping the element to suspendthe blade in its hanging position, means operable from a point adjacentthe floor level for operating the gripping device to release and locksaid element, and meansbelow the hanging blade for measuring thevariation between a mark on the physical axis and the vertical line ofthe hanging center at the tip of the blade.

13. Apparatus for use in making propeller blades providedwith a shankfor connection to a hub comprising, a supporting structure including apair of rigid columns extended upwardly from a working floor and spacedapart laterally to provide between them space for hanging ,the blade, anoverhead guide on the structure, a flexible suspension element for theblade extending around said guide and having a free depending portionbetween the columns, means for detachably supporting the blade on theend of the depending portion of the element, hoistingmechainismzsupported on thesstructureand to which the element isconnected for raising the blade into hanging position between.thecolumns, an over.- head device-on the supporting-structure forgripping the element to suspend the blade in its hanging position, meansoperable .from' a .point adjacent the floor level for operatingthegripping :device to release and lock said element, and aneans belowthe hanging blade-for measuring the variation between a mark on thephysical axis sand the vertical line of the hanging centera't the tip of:the blade.

14..Me'ans .for hangingra propeller blade with a tubular shank fromarlfiexible suspension ele- :ment comprising, .a body provided with a:memberiadaptedito extend into :the shank of the propeller. a :fiange onsaidbody, gripping members slida'blym'ounted insaid body forinternallylgripping the'shank, a sleeve provided with means forexpanding said members and slidably mounted in said :bodma nut threadedtos'aid sleeve for shiftlnglit-to expand said gripping members, :abearing-member in the sleeve having a downwardly facing conicalsurfacaiafstem provided'with contractible jaws for gripping said elementand a thimble 'extendingin'to the sleeve and having means atits upperend for engaging the conical surface on the bearing-member andmeans forcontracting the jawsgtheithimbleiand'stem being connected :by a screwthread, the sleeve, thimble and stem :being provided with an openingthrough which said. element passes.

15. devicei'for supporting a propeller blade havinga tubularv shank'jroma flexible suspension element provided :with an abutment comprising, abodyadapted to sextend into the shank of tthexz blade elements mountedto slide radially in said.ibody i'for internally gripping the shank, a.sleeve slidably mounted in .and extending through said body and providedwith means for spreading the gripping elements, a .-.nut on the sleevefor shifting the sleeve in the body, and a bearing in :the sleeve for'tiltably supporting the device and blade from the abutment on thesuspensionelement.

T16. Adevice for supportinga propeller blade having-a tubular shank froma flexible suspension Ielement provided with an abutment, comprising,abody adapted to extend into the shank V of the blade, elements mounted:to slide radially in said body for internally gripping the shank, aholdingflange-on the body on the outside of the blade, a sleeveslidablymounted in, and-extending through said body and provided withmeans for spreading the gripping elements, a nut .on' the sleeve forshiftin thesleeve in the body, and :a bearing in the sleeve for'tiltably supporting the device and blade from the abutment'onthesuspension'element.

17; Means :for hanging-a propeller blade provided with atubular shank,.from a flexible suspension element so it will be free tohang'vertically, comprising: a device including means for detachablygripping said element and provided with a bearing; a device including abody insertableinto the shank of the blade, means carried by the bodyfor internally gripping the shank, andla'bearing fixed in said-bodyas asupport therefor having a bore which is .clear of the element; saidbearings being separable andprovided with engaging faces for universaltilting o'i,.an'd.solelysupporting, the blade and the blade grippingdevice on the element gripping. device,

so that the blade will be free to hangiverticallyc 18. Means. forhanging a propeller :blade provided with a tubular shank, from afflexible ssuspension-element so it will be free to hang vertically,comprising: adevice including means for detachably' gripping saidelement and provided with :a bearing; 'a device including a body in.-sortable into the shank of the blade, meanscarried by the body forinternally gripping the shank, and a'bearing rfixedinthebody as .a.;supvport therefor having an opening "for clearing the element; said bearingsbeing separable and provided withconioal and arcuate-engagingdaces foruniversal tilting of, .and solely-supporting, the blade and the bladegripping device :on the element gripping device so that the blade willibe free to hang vertically.

'19. Means for hanging a propeller blade provided with a tubular'shank,from a flexible suspension element so it will be free to hangvertically, comprising: a device including means 'for detachablygripping said element and provided with a:bearing;,a device includingatubular body .insertable into the shank of the blade, expansible jawscarried by the body for gripping-the shank, a member slidably mounted inthe body for exhanding the jaws for, internally gripping the shank, anda bearing fixed in said body as -.a support therefor having a bore whichis'clear :of the element; said bearings being separable .and providedwith engaging faces in said member.f0r universal tilting of, and solelysupporting the blade and the blade gripping device :on the :elementgripping device so that the blade will:.be free to hang vertically,

20. Means for hanging a propeller blade provided with a tubular shank,from .a flexiblesuspension element so it will be free to hangvertisally, comprising: a device including means :for detachablygripping said element and provided with'a bearing; a device including'atubular body insertable into the shank of the blade, means in the body'for internally gripping the shank, and a bearing "having a bore whichis clear 'of the element, said element gripping :member being adapted toextend into the tubular body, said bearings being disposed inthetubularbody, and being separable andprovided with engaging faces foruniversal tilting of, and solely supporting the blade and the bladegripping device on the element gripping device so that the .blade willhe free tohang vertically.

' LEROY B. CHUBB.

REFERENCES CITED The following references :are so'f record in the fileof this patent:

I UNITED STATES PATENTS

